Conventional carburetors are equipments that mix the proportional gasoline with air in a vacuum condition generated by an engine so as to supply mixed gas to the engine. The carburetor is called as a heart of the engine due to its significant function. The carburetor includes a start-up device, an idling device and a throttle control device, etc., and the carburetor can automatically prepare the desired mixed gas accordingly to different working status of the engine and output the mixed gas, further, the carburetor may atomize the fuel oil to make sure the uniformity of the mixed gas.
For maintaining the stable operation for the carburetor in the best proportion of fuel oil and air, the manufacturer will adjust the mixture proportion of the fuel oil and air when carburetor is made. In such a way, the carburetor can exert its best operation performance to extend its normal using lifetime and significantly save fuel oil resource. Thus it's necessary to configure a structure to prevent non-professional user from casually adjusting the mixture proportion of the fuel oil and the air on the carburetor. However, the conventional carburetor could not make it. For example, a carburetor with rotary valve has an idle needle with a head, and a steel ball is configured above the head, however, this structure is complicated and the manufacturer could not adjust the idle needle if the technical parameters of the carburetor are required to regulate.